1. Field of the Invention
The present invention relates, in general, to sawmills, and in particular, to apparatus for trimming the edges of boards before removal from a log, as well as a to a mast for slidably supporting the cutting means that trim the edges of the boards.
2. Information Disclosure Statement
Sawmills are well known which saw boards from logs. However, the removed boards need to have edges formed on the two sides not cut by the main head saw. Prior known methods for edging boards in a sawmill utilize a vertical shaft with upper and lower blades which move up and down on the shaft for forming the edges of the board to be removed. Prior methods do not automatically size the log, and therefore either require multiple passes of the log if the sizing blades were set too wide, or waste portions of the log by forming a board which is more narrow than necessary if the sizing blades were set too closely.
It is therefore desirable to have an edger which can chip or cut the edges from boards in a sawmill, producing wood chips which can then be used for other purposes such as making paper or as fuel wood. It is also desirable that the sizing of the board and the determination of the correct top and bottom edges of the board be performed automatically, without any guesswork on the part of an operator, and that means be provided for automatically positioning upper and lower cutters where they will cut or chip upper and lower edges from the board at points corresponding to the narrowest vertical dimensions of the log. Furthermore, by utilizing well-known industry grading rules for logs, it is desirable that the edges of the board can be placed so that a maximum-value board will result.
It is further desirable to have a mast capable of slidably supporting and positioning motors that directly drive edging saws or chippers attached to the shafts of the motors. While prior apparatus are known, as mentioned above, that provide for saw blades sliding up and down a vertically rotating shaft, they are not capable of supporting the significant weight of motors that drive the saw blades, thereby precluding the slidable support of such motors.
A preliminary patentability search in Class 144, subclasses 369 and 370, produced the following patents, some of which may be relevant to the present invention: Griffin, U.S. Pat. No. 3,204,675, issued Sep. 7, 1965; Nilsson, U.S. Pat. No. 3,692,074, issued Sep. 19, 1972; Mallery, U.S. Pat. No. 3,880,215, issued Apr. 29, 1975; Pease, U.S. Pat. No. 3,977,447, issued Aug. 31, 1976; Shepard, U.S. Pat. No. 4,015,648, issued Apr. 5, 1977; Reuter, U.S. Pat. No. 4,335,767, issued Jun. 22, 1982; Reuter, U.S. Pat. No. 4,848,427, issued Jul. 18, 1989; and Andersen, U.S. Pat. No. 4,895,197, issued Jan. 23, 1990.
Additionally, during the prosecution of the parent to this application's parent, the following patents were cited by the Examiner: Reuter, U.S. Pat. No. 4,907,632, issued Mar. 13, 1990; and Stroud, U.S. Pat. No. 4,947,909, issued Aug. 14, 1990. Furthermore, applicant has recently become aware of Jenks, U.S. Pat. No. 4,541,722, issued Sep. 17, 1985.
Applicant also knows of an optical triangulation probe sold in the United States under the trademark "SELCOM OPTOCATOR" by Selective Electronic, Inc., P.O. Box 250, Valdese, N.C. 28690, that is used in the logging industry to measure the position of logs passing through a sawmill.
While each of the above references disclose various sawmill edgers and apparatus, none disclose or suggest the present invention. More specifically, none of the above references disclose or suggest an edger for use with a conventional sawmill, said edger comprising upper and lower cutting means for forming the upper and lower edges, respectively, of a board to be removed from a log, each said cutting means comprising: a rotatable blade, means for rotating the blade, and positioning means for moving the blade upwardly and downwardly with respect to the log and for positioning the blade for cutting the respective edge of the board when the blade is placed in contact with the log; said edger additionally comprising sizing means for automatically determining the placement of the upper and lower edges of the board to be removed from the log; and, control means, responsive to said sizing means, for controlling the moving and positioning of the blade of each said cutting means by each said positioning means.
Likewise, none of the above references disclose or suggest an edger for use with a conventional sawmill, said edger comprising: a vertically upright mast; upper and lower cutting means for forming the upper and lower edges, respectively, of a board to be removed from a log, each said cutting means comprising: a rotatable blade; a carriage; sliding attachment mean for slidably mounting said carriage on said mast for upward and downward movement thereupon; rotation means, mounted on said carriage, for rotating the blade; and positioning mean for moving the carriage upwardly and downwardly with respect to the log and for positioning the blade for cutting the respective edge of the board when the blade is placed in contact with the log.
Griffin, U.S. Pat. No. 3,204,675, describes chippers which mill opposing sides off boards. The Griffin device does not work in conjunction with a sawmill, but instead replaces the saw, and does not form boards or the edges of boards, but rather mills the log into a square post.
Nilsson, U.S. Pat. No. 3,692,074, describes a chipping and sawing machine that forms opposite planar surfaces on a log, said surfaces being parallel to the cuts that will be made by a saw blade. The Nilsson invention does not form the edges of the board as does the present invention.
Mallery, U.S. Pat. No. 3,880,215, describes a wood chipper that removes the rough outer surface or slab from a log, forming the planar outer surface of the first board to be cut, but also does not form the edges of the board.
Pease, U.S. Pat. No. 3,977,447, describes a single chipper blade assembly of piecewise varying radius which simultaneously chips three sides of wood scrap having a fourth flat side, forming a board.
Shepard, U.S. Pat. No. 4,015,648, describes a sawmill with a pair of chipping edger blades mounted on a single shaft. The chipper blades form the edges of the board, as does the present invention, but the Shepard device does not have the ability to automatically size the log and adjust the placement of the chipper blades correspondingly.
Reuter, U.S. Pat. No. 4,335,767, describes a method and apparatus for sawing and milling four-sided timber using a pair of carriage-mounted adjustable milling heads and a pair of opposed cutting blades. The Reuter apparatus does not work in conjunction with a conventional sawmill, and discloses no automatic sizing mechanism such as that which is a part of the present invention.
Reuter, U.S. Pat. No. 4,848,427, improves on the above-mentioned prior Reuter patent, and describes an apparatus to cut corners into logs which will form board edges. Still, no automatic sizing mechanism is described.
Andersen, U.S. Pat. No. 4,895,197, describes a method and apparatus for sawing boards from a log at various angles so as to avoid wastage, making two blind cuts into the log which are then connected with a third, longitudinal, cut to form the board, then rotating the log to a new position for removal of another board at a new angle.
Reuter, U.S. Pat. No. 4,907,632, describes a feed apparatus having rollers that move a log through a sawmill. A scanning roller mounted on a pivoted arm is disclosed that contacts the surface of the log, generating a signal that is used to center the log on the feed rollers.
Stroud, U.S. Pat. No. 4,947,909, describes computerized horizontal and vertical scanners that view the outer surface of a log to determine the horizontal and vertical diameters as well as the position of the centerline of the log, and a process to use this information to position cutting heads as the log passes through the sawmill.
Jenks, U.S. Pat. No. 4,541,722, describes a contour line scanner for profiling log cants. A pair of fan-like lasers project coplanar contour lines on the log cant that are then viewed by an overhead camera. The position of the contour lines on the log can be moved, and the resulting grade of a cut board determined. The present invention does not use fan-like lasers to project movable contour lines on the log.